Synthesis and Electrochemical Characterization of NaCoO2 as Cathode Material in 2 M NaOH Aqueous Electrolyte

Abstract This work reports an electro‐analytical study of NaCoO 2 as cathode material synthesized by a low‐temperature combustion method for aqueous sodium‐ion batteries. The synthesized cathode material was electrochemically characterized in 2 M NaOH aqueous electrolyte. The obtained material‘s physical characteristics are investigated by X‐Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X‐ray analysis (EDX), Thermo‐Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) to evaluate its crystal structure, crystal size, composition, and surface morphology. From SEM images, the crystal size of the synthesized NaCoO 2 is found to be varying between 50–100 nm with good crystallinity. From TGA studies, the material shows thermal stability up to around 300 °C with maximum weight loss at about 375 °C. Electrochemical behaviour of NaCoO 2 in 2 M aqueous sodium electrolytes are evaluated using cyclic voltammetry and galvanostatic charge‐discharge techniques. The cell, NaTi 2 (PO 4 ) 3 /2 M NaOH/NaCoO 2 constructed in aqueous 2 M NaOH is found to deliver a discharge capacity of 89 mAh g −1 at C /10 rate. It retains its initial capacity over 55 cycles and at a high C rate of 1 C a discharge capacity of 34 mAh g −1 was obtained which can be compared with that obtained for NaCoO 2 in non‐aqueous battery systems.